Constraining long-lived particles: Mass exclusion limits via CheckMATE analysis

Abstract

This study utilized CheckMATE, a framework that tests generated events of proposed models against the current findings of the Large Hadron Collider (LHC), to establish an exclusion plot for the allowable mass pairs of the Z′ boson and the long-lived particle (LLP) X2. The exclusion plot serves as a crucial reference for theorists seeking to develop BSM models incorporating Z′ and X2 with specific mass values which is especially the case for theories proposing extensions of the electroweak symmetry. Events were generated using MadGraph 5 (MG5), a Monte Carlo generator used in high energy physics, in which the decay mode was specified to have protons undergo X2 X2^~ pair production with Z′ as the mediator particle. The event files obtained from MG5 were fed into CheckMATE to be tested against the current data at the LHC. The results were then plotted by implementing the interpolation method in Mathematica using the corresponding r-value for each event. It was observed that allowed mass pairs occur at regions of high compression where the mass of the parent and daughter particles have nearly the same value. The mapped bounds of the mass-mass exclusion plot serve as an original result that can be used as a benchmark for the development of future models involving LLP production via Z′ as well as for experimental searches in the dedicated LLP detectors.